Metabolites associated with mucus hydration and adenosine metabolism could be strong markers of chronic obstructive pulmonary disease (COPD) severity,  problems with lung function, symptoms of bronchitis, and pulmonary exacerbation, and these markers need to be added in the pathology of COPD. A recent study conducted by Dr Charles R Esther and team from the Pediatric Pulmonology Clinical Operations, University of North Carolina at Chapel Hill, found that the metabolites associated with mucus hydration and adenosine metabolism such as sialic acid, hypoxanthine, xanthine, methylthioadenosine, adenine, and glutathione were strongly linked with markers of COPD severity, including lung function, symptoms of bronchitis, and pulmonary exacerbation. The study, published in CHEST, aimed to gather a better understanding of the physiological pathways that lead to airway diseases and damage, observed that the most significant elevations in COPD sputa were with these six metabolites. The report also highlighted that the research team observed that metabolites within other pathways, including methionine salvage and oxidative stress, were also associated with COPD severity, though not as strongly. The scientists said in the report that these findings emphasize the importance of mucus hydration in the pathology of COPD.